A tremendous amount of engineering and technical knowledge goes into designing, building and implementing a wireless communication system, such as a cellular communication system. Equally impressive is the amount of engineering and technical knowledge required to operate and maintain the communication system once implemented.
A cellular communication system, for example, is a complex network of systems and elements. A minimum number of elements include 1) a radio link to the subscriber units (cellular telephones) which is usually provided by at least one and typically several base transceiver stations (BTS), 2) a communication link between the base transceiver stations, 3) a controller, typically one or more base station controllers or centralized base station controllers (BSC/CBSC), to control communication between and to manage the operation and interaction of the base transceiver stations, 4) a call controller or switch, typically a mobile switching center (MSC), for routing calls within the system, and 5) a link to the land line or public switch telephone system (PSTN) which is usually also provided by the MSC.
Within each of these elements are numerous subsystems and components. For example, a base station will at least include radio frequency power amplifiers, frequency synthesizers, signal converters, modems, power supplies, fans, etc. A CBSC, for example, may include a mobility manager, voice coders, echo cancellers, and may further provide a link to an operations and maintenance center (OMC). The MSC includes systems for switching calls and for providing call related services such as call waiting, call forwarding, voice mail, and the like. Needless to say there are a lot of systems, subsystems, system elements and components that have to function and interact properly for the cellular communication system to work.
When things go wrong in the cellular communication system there are a number of indications. For example, audible and visual indicators (alarms and flashing lights) may activate indicating one or more elements are not functioning properly. Network performance statistics, observed by the cell network operator, may move outside a normal operating range thus indicating that performance of the network is less than optimal and hence suggesting a problem with the system. Each of these indications tell the system operator that something is wrong with the cellular communication system. What these indications do not necessarily tell the operator is what is wrong and how to fix it. And, the large volume of data generated within the communication system and the complexity of the data often exceeds the processing capability of the operators. This leaves the system operators unable to effectively manage the system.
The typical response to a problem is to observe the alarm or alarms, and to react to whatever it is generating the alarm condition. This is known as fault based reaction. Several systems have recently been proposed attempting to automate the fault based reaction process. However, every alarm does not necessarily sound a problem. A situation known as sympathetic alarming may occur where because an alarm condition exists with one element, alarm conditions occur in other elements sometimes only remotely related to the initial alarm condition. Whether an alarm is indicating an actual problem or a sympathetic situation requires additional investigation. The automated fault management systems have attempted, with limited success, to reduce the effect of sympathetic alarms by providing what is known as alarm correlation. But, investigation by the system operator is still required to finally determine the problem with the system.
With years of experience, cell network operators learn that certain observed conditions relating to the operation of the network arise from the occurrence of certain events. Thus, given a set of circumstances, an experienced operator can by observing the condition predict one or more causes of the condition regardless of which alarms are sounding. This knowledge, however, is associated personally with the expert, and is unavailable when the expert is unavailable.
Thus two problems persist. First, how does one in a simple, convenient and reliable manner gather knowledge from the system experts. Second, how can this knowledge be organized such that a non-expert may refer to the knowledge to efficiently operate and manage the communication system.